Determination of Melatonin in Rat Pineal Gland and Drug with Flow‐Injection Chemiluminescence

Abstract

AbstractA flow‐injection chemiluminescence (CL) method for the determination of melatonin based on the CL reaction of melatonin with hydrogen peroxide and sodium hypochlorite (NaOCl) in a basic alkaline solution was developed. The possible CL mechanism has been discussed, and a proposal for the reaction pathway was given that singlet oxygen was clarified to be produced in this reaction system and was responsible for the CL emission. Under the optimized conditions, the linear concentration range of application was 1.0×10−7–2.5×10−4 mol·L−1 with a detection limit of 5.0×10−8 mol·L−1 (S/N=3). The relative standard deviation for eight repeated measurements of 1.0×10−6 mol·L−1 melatonin was 2.8%. The interferences of several important biological substances, some indole compound, cations and anions were studied. No interference was found for the anions, glucose, starch, most of cations and low concentration (less than 3.0×10−6 mol·L−1) of some biological substances and indole compound. The method was applied to the determination of melatonin in rat pineal gland and drug with satisfactory results. The sample throughput was 90 injections per hour.